Switch mechanism



p 1954 J. K. TOM

SWITCH MECHANISM Filed Dec. 26. 1950 INVEN TOR. By JAMES K. TOM WATTORNEY fi lr vrllllllfllll 1 Patented Sept. 21, 1954 SWITCH MECHANISMJames K. Tom, South Bend, Ind., assignor to Bendix AviationCorporation,South Bend, Ind., a corporation of Delaware Application December 26,1950, Serial No. 202,714

Claims.

1 This invention relates to an improved snap switch'mechanism adaptedfor use in .the controls of an automotive vehicle for example a brakecontrol mechanism of the vehicle.

An important object of my invention is to provide a switch operatingmechanism operable to insure the operation of the switch, preferably aclosing thereof, and also operable to insure a fast operation of theswitch. Electrical switches of various kinds are now in use and arefrequently employed to control the circuit supplying current to thevalve operating solenoid of the anti-creep mechanism of an automotivevehicle. However said switches are ofttimes operated 'by mechanism, suchas centrifugally operated weights or fluid pressure responsive means,which is not uniform in operation, for example does not always operateat the same time before or after the vehicle comes to a stop. Ifpressure responsive means such as a diaphragm operating fluid is usedtooperate the switch then variations in temperature of the fluid willeffect its viscosity and density thereby affecting the time of operationof the switch; and if centrifugally operable means is employed tooperate the switch then such a means may be ineifective at low vehiclespeeds and may not be sensitive enough for an eifective operation of theswitch.

It is accordingly an object of my invention to provide a switchmechanism wherein the switch of the mechanism is both certain ofoperation and certain of a speedy operation. The latter feature of myinvention insures a switch mechanism which is free of the deleteriouseffects of excessive arcing of the switch.

My invention also contemplates the provision of an efiective snap actingmechanism especially adapted for use in electrical switches.

It is another object of my invention to provide a simple, compact, andeffective switch mechanism of relatively few parts and thereby capableof being easily serviced and constructed ata minimum of cost.

The above and other objects and features of my invention will appearmore fully hereinafter parts thereof being in their positions just priorto a switch closing operation of the mechanism; Figure 3 is a viewsimilar to Figure 2 disclosing the switch operating cam member andassociated parts in their cam cocked position;

Figure 4 discloses the position of the parts of the mechanism during theoperation of the cam to close the switch; and

Figure 5 discloses the parts of the mechanism just after the operationof the switch has been completed.

Referring now to the figures of the drawing disclosing a preferredembodiment of my invention there is disclosed in Figure 1 a casingcomprising a 'cup shaped body portion [0 and a cap member l2 the baseportion of the body member being bored to receive a switch operatingdriving member l4 preferably a rotatable two diametered shaft ofsuitable material. To this driving member [4 there is secured a flange[6 having a driving pin l8 extending laterally therefrom. A switchoperating driven member, preferably a cam member 211 constructed ofelectrical nonconductive material, is rotatably mounted on the smallerdiametered portion ll of the shaft i4 and parallel to the flange l6; andthis cam member is recessed at 28 to receive the upper end of the pin[8. The recess 28 of the cam, together with cooperating parts of theswitch operation mechanism, insures a'certain desired lost motionoperation of the mechanism which operation will become evident from thedescription to follow.

A coil spring 22 or other suitable yieldable member is sleeved over theshaft [4 one end 24 of the spring being biased into abutment with thepin l8 and the other end 26 of the spring being secured to the cammember 20. It follows therefore that the spring 22 is preloaded prior toassembling the parts of the mechanism. This spring 22 provides ayieldable connection between the driving and driven members of theswitch operating mechanism of my invention. Completing the descriptionof the switch operating portion of the switch mechanism of my inventiona yieldable stop member 36, stronger than the vspring 22, is securedat32 to the switch casing,

and said stop memberds preferably. crimped at its end toprovide"a.2portion 33 which is contacted by a lobe portion 34 of thecamifl.

Describing now the switch portion of the mechanism of my invention afixed switch contact member 36 is secured to a yieldable member 38 whichis secured at one of its ends to a post 40 secured to a member 42,Figure 1, of electrical non-conductive material such as Bakelite. Themovable contact 44 of the switch mechanism is secured to a member 46which is in turn yieldably secured, by a spring 48, to a post 50 whichis secured to the member 42. The spring 88 serves to bias the contactsupport member it downwardly, Figures 2 to .5 inclusive, into contactwith a stop 52 which is secured to the member 42. The contact supportmembers 38 and 46 and the posts 40 and 50 are preferably of electricallyconductive material thereby providing means for circuiting the flow ofelectricity through the switch mechanism.

The switch portion of the switching mechanism of my invention alsoincludes the cap member 12 detachably mounted on the switch body portion10, said cap member serving as a support for contact posts 54 and 56. Tothe post 56 there is secured an electrical conductor 58 which contactsthe post 40 and to the post 54 there is secured an electrical conductor60 which contacts the post 50.

Describing now the operation of the mechanism of my invention it is tobe remembered that the spring 22 is preloaded accordingly the endportion 24 thereof is biased into abutment with the driving pin 18 andthe end portion 25 serves to bias the cam 20 into abutment with saidpin, the flange [6, pin 18, cam 20, and spring 22, taking the relativepositions disclosed in Figure 2; and it will now be assumed that theshaft l4 has been rotated until the cam lobe 34 strikes the end portion33 of the stop 30. Now it is to be remembered that the yieldable stop 30is stronger than the spring 22 accordingly a continued rotation of thedrive shaft l4 serves to place the parts of the mechanism in theposition disclosed in Figure 3 wherein the preloaded spring 22 isfurther cooked and the pin 18 is nested within the left hand corner ofthe recess 28.

Continued rotation of the drive shaft will then force cam 20 to rotate,the stop member 30 yielding to permit this operation; and after the camlobe 34 has cleared end 33 then the cocked spring 22 will operate toquickly rotate the cam relative to the flange 16 until the pin I8 isnested within the right hand end portion of the recess 28 as disclosedin Figure 5. Now this trigger like operation or snap action serves tomomentarily close the switch 36, 44 this closing operation beingdisclosed in Figure 4 of the drawing. The closing is however quitemomentary inasmuch as the spring 48 biases the contact support member 43into contact with the stop 52 and when said member is in this positionthe contacts 36, 44 are spaced from each other as disclosed in Figure 2.

After the switch closing operation has been completed, that is after thelobe 34 has rotated past a portion 34' of the member 46, the partsassume the switch open position disclosed in Figure and continuedrotation of the drive shaft will then rotate the cam, the shaft and cammoving as a unit; and this rotation continues until the parts againassume the positions disclosed in Figure 2.

There is thus provided an effective snap action switch mechanism whichis, by virtue of the fast rotation of the cam relative to the flange l6and the spring like operation of the support member 46, certain ofoperation whether the switch 35, 34 be opened or closed by saidoperation. The switch disclosed in the drawings is closed by theoperation of the mechanism however said switch might be constructed tobe opened by said operation. Suffice it to say that the switch mechanismof my invention is cheaply constructed, easily serviced, is effectiveand provides a switch mechanism wherein the switch is both certain ofoperation and quick of operation.

Although only one embodiment of my invention has been illustrated anddescribed various changes in form and relative arrangement of parts maybe made to suit requirements.

I claim:

1. An electrical switch mechanism comprising a casing, a switchmechanism mounted in the casing, and means within the casing foroperating the switch mechanism including rotatably mounted driving meansincluding a driving shaft and a flange member secured to the shaft,switch operating driven means rotatably mounted on the driving means,and means providing a lost motion connection between the two meansincludin a coiled spring operatively connected to the flange memberoperable, after being cocked, to effect a. relatively rapid movement ofthe driven means with respect to the driving means in the operation ofoperating the switch.

2. An electrical switch mechanism comprising a casing, switch meansmounted within the casing and snap acting switch operating means withinthe casing including a drive shaft and a flang member secured to theshaft, a switch operatin cam rotatably mounted on the shaft, and means,including a preloaded coil spring having one of its ends secured to thecam and the other of its ends operably connected to the flange member,providing a yieldable driving connection between the drive shaft andcam.

3. An electrical switch mechanism comprising a casing, switch meansmounted within the casing, and snap acting switch operating means withinthe casing including a drive shaft, a driving flange secured to theshaft, a drive pin secured to the flange, a switch operating camrotatably mounted on the shaft, and means, including a preloaded coilspring having one of its ends secured to the cam and the other of itsends abutting the pin, said means providing a yieldable drivingconnection between the drive shaft and cam.

4. In an electrical switching apparatus, a casing, and switch operatingmechanism within the casing including driving means rotatably mountedWithin the casing, a switch operating driven member rotatably mounted onthe driving member, means constituting a drive connection between thedriven member and driving means, said connecting means including a pinmounted on a portion of the driving means and further including ayieldable means having one of its ends abutting the pin and the other ofits ends secured to the driven member, together with yieldable stopmeans stronger than the yieldable means, said stop means cooperatingwith the yieldable means to control the operation of the driven member.

5. An electrical switching apparatus including a casing and switchoperating mechanism within the casing including driving means rotatablymounted within the casing, a switch operating driven member rotatablymounted on the driving member, means constituting a drive connectionbetween the driven member and driving means, said connecting meansincluding a pin mounted on the portion of the driving means and furtherincluding a coil spring mounted on a portion of the driving member saidspring having one of its ends secured to the driven member and the otherof its ends abutting the pin, together with yieldable stop meansstronger than the coil spring said stop means cooperating with the coilspring to control the operation of the driven member.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 816,083 Farwell Mar. 27, 1906 1,176,794 Uhl Mar. 28, 19161,916,485 Manrodt July 4, 1933 2,086,800 Harris July 13, 1937

